Machine for forming glued folding boxes



June 12, 1962 E. J. PAGENDARM MACHINE FOR FORMING GLUED FOLDING BOXES l5 Sheets-Sheet 1 Filed March 6, 1959 I N VEN TOR. Edward J. Pagendarm ATTORNEY June 12, 1962 E. J. PAGENDARM' 4 3,038,389

MACHINE FOR FORMING GLUED FOLDING BOXES Filed March 6, 1959 15 Sheets-Sheet 2 I N V EN TOR. Ec/wa ra J. Page dam? ATTORNEY- June 12, 1962 J. PAGENDARM 3, 8

MACHINE FOR FORMING GLUED FOLDING BOXES l5 Sheets-Sheet 3 Filed March 6, 1959 INVENTOR. Edward J. Pagendarm A TTORNE Y' June' 12, 1962 J. PAGENDARM MACHINE FOR FORMING GLUED FOLDING BOXES l5 Sheets-Sheet 4 Filed March 6, 1959 I ATTORNEY June 12, 1962 E. J. PAGENDARM 3,038,389

MACHINE FOR FORMING GLUED FOLDING BOXES Filed March 6, 1959 15 Sheets-Sheet 5 INVTUR Edward J. Page/1 dqrm 4M ATTORNEY June 1962 E. J. PAGENDARM 3,038,389

MACHINE FOR FORMING GLUED FOLDING BOXES Filed March 6, 1959 l5 Sheets-Sheet 6 INVENTOR. Edward J. Pagendarm BY ('4 A TTOR/VEY June 12, 1962 v E. J; PAGENDARM 3,038,389

MACHINE FOR FORMING GLUED FOLDING BOXES Filed March 6, 1959 15 Sheets-Sheet 7 F 8 I NVENTOR.

Edward J Pagendarm (4M ATTORNEY June 12, 1962 E. J. PAGENDIAIEQM 3, 3

MACHINE FOR FORMING GLUED FOLDING BOXES Filed March 6, 1959 l5 Sheets-Sheet 8 IN V EN TOR. Edward J Pagenc/arm ATTORNEY June 12, 1 2 E. J. PAGENDA'RM 3,038 389 MACHINE FOR FORMING GLUED FOLDING BOXES Filed March 6, 1959 15 Sheets-Sheet 9 INVEN TOR. Edward J. Pagendafm A TTORNEY June 12, 1962 E. J. PAGENDARM MACHINE FOR FORMING GLUED FOLDING BOXES l5 Sheets-Sheet 10 Filed March 6, 1959 INVEN TOR. Edward J Pagendarm {bu-MM ATTORNEY M mu INVENTOR.

ll nw NY E. J. PAGENDARM MACHINE FOR FORMING GLUED FOLDING BOXES June 12, 1962 15 Sheets-Sheet 11 Filed March 6, 1959 Pg? 73 Edward J. Pagenfl'arm A v A TTORNEY June 12, 1962 E. J. PAGENDARM 3,038,389

MACHINE FOR FORMING GLUED FOLDING BOXES Filed March 6, 1959 15 Sheets-Sheet 12 nub w INVENTOR.. F 75 Edward J. Pagendarm H-OWA A TTOR/IEY June 12, 1962 E. J. PAGENDARM 3,038,389

MACHINE FOR FORMING GLUED FOLDING BOXES Filed March 6, 1959 15 Sheets-Sheet 13 I N VEN TOR. 61 ward J Pagendar w A TTORNEY June 12, 1962 J. PAGENDARM MACHINE FOR FORMING GLUED FOLDING BOXES 7 15 Sheets-Sheet 14 Filed March 6, 1959 INVENTOR. Edward J. Pagendarm BY H 1 A TT'ORNE) Julie 12, 1962 E. J. PAGENDARM 3,038,389

MACHINE FOR FORMING GLUED FOLDING BOXES Filed March 6, 1959 '15 Sheets-Sheet 15 IN V EN TOR. Edward J. Pa enaarm ATTORNEY ilnited States Patent 6 3,ti38,389 MACHINE FOR FGRMINS GLUED FOLDING BOXE Edward J. Pagendarm, San Mateo, Calif, assignor, by mesne assignments, to Atlas General Industries, Inc., a corporation of Massachusetts Filed Mar. 6, H59, Ser. No. 797,638 34 Claims. (Cl. 93--51) This invention relates to the art of making folding boxes by folding an appropriately shaped box blank and adhesively securing certain of its poritons together in box forming position.

Conventional box making machines comprises basically a conveyor which moves an initially flat box blank past adhesive applying and folding devices, whereafter the box passes into a pressure section in which the glued portions are maintained under pressure until the adhesive bond has become sufliciently strong to permit the box to be discharged from the machine. These machines are relatively extended and occupy a large amount of floor space.

It has been proposed to reduce the length of the box making machine by use of a box folding mechanism of the plunger and die type, preceded by a conventional conveyor portion flanked by prefolding mechanism and glue wheels. In the known machines one purpose of the prefolding mechanism is to move certain portions of the box blank out of engagement with the glue wheels and another purpose is to prepare the blank for the sub sequent folding operation performed in the plunger and die mechanism.

Adhesive applicators of the wheel type have numerous disadvantages, among which may be mentioned the tendency of the wheels to pick up board dust, which is everpresent in a box plant, and necessitates frequent cleaning of the glue applicator. Glue Wheels exposed the adhesive to the atmospheric air by reason of the large surface of the adhesive coated area of the wheel and, as a consequence, the adhesive oxidizes and deteriorates rapidly. The nightly shut-down of the machine causes portions of the glue wheels to dry up, a disadvantage which is noticeable even after relatively brief shut-down, such as the lunch hour shut-down of the machine.

Conventional glue wheels generally apply the adhesive in strip form from one outer edge of the flap or panel to which the adhesive is applied to the opposite edge. This is normally not disadvantageous where there is a substantial lapse of time between the applicataion of the adhesive and the application of pressure in the pressure section, and where the pressure is neither severe nor applied so suddenly that the adhesive near the edges of the blank or panel is squeezed out beyond the edge of the panel.

In a machine of the plunger and die type, however, a relatively great compressive force is applied rather suddenly by contraction of the die, resulting in squeezing of adhesive beyond the edge of the flap or panel, thereby soiling the box and the die. Adhesive deposited on the die surfaces interferes with the operation of the machine and necessitates periodic shut-down of the machine for cleaning purposes.

The present invention permits a box folding and gluing machine to be built of very compact size requiring a floor space of the order of five by five feet.

Folding and compression of the box is accomplished by a plunger and die mechanism into which the fiat blank is fed. A measured quantity of adhesive is applied to the blank in a predetermined pattern, which is preferably so laid out that the adhesive is never squeezed beyond the edges of the flaps or panels to be adhesively secured, even though the compressive force is very high and is suddenly applied.

3,638,389 Patented June 12, 1962 ll Q6 The invention permits use of very fast drying adhesive compositions by depositing the adhesive in slow drying drop or bead form, rather than as a quick drying thin film exposed to air. The drops or beads are converted into the form of a thin film by contact of the surfaces which are to be adhesively secured. This contact takes place under high pressure and causes the deposited quantity of adhesive to be spread out as a thin film.

The present invention permits the time between the application of the adhesive and the actual formation of the glue bond to be made extremely short, of the order of a fraction of a second. The high compressive force which is applied to the glue bond produces a very thin glue film between the surfaces to be adhered. Such a film sets almost instantly and permits the box to be discharged immediately thereafter. This, in turn, results in a high productive rate.

Preferably the step of applying adhesive is combined with the step of prefolding the blank. This permits the adhesive applicator to be constructed as a portion of a prefolding mechanism against which the flat blank is moved. The transport of the blank may be accomplished by a combination feeder and plunger which comes to rest sufficiently long to permit a pattern of adhesive to be applied to a stationary blank. Preferably a feeder is employed which is distinct and separate from the plunger which subsequently forms the box. In the preferred arrangement the blank is moved into the path of the plunger by the blank feeder which then releases the blank so that the blank comes to rest for a brief moment during which the adhesive pattern is applied far more accurately than if the blank were in motion.

The invention further makes possible an arrangement for discharging adhesive only when a blank is present, so that the discharge of adhesive is suspended when the supply of blanks is interrupted.

At first impression it would seem a simple matter to accomplish this by installing a device responsive to the presence of a blank at the station where adhesive is to be applied, in the present case the mouth of the folding die. In actual practice, however, this is not practicable in a rapidly operating machine because the time is not sufficient to render the adhesive applicator effective or ineffective once the blank has arrived at the mouth of the die. The moving parts of the control mechanism have a certain mass and present acceleration and inertia problems which do not permit actuation in response to a signal developed at the mouth of the die.

According to one aspect of the present invention a control signal is developed during the feeding of the blank by the mechanism which transports the blank from the magazine to the die. Here a problem is encountered due to the fact that the blank feeder has actually released the blank at the moment adhesive is to be applied. The blank feeder itself therefore is in the same condition at that moment as if no blank had been fed during the preceding cycle. According to the present invention the signal is derived prior to the application of the adhesive and is then stored until after release of the blank by the feeder. This arrangement leaves suflicient time for the mechanism which controls or operates the adhesive applicator to be moved into an operative or inoperative position depending on the presence or absence of .a blank on the feeder prior to the arrival of the blank at the mouth of the die.

These and various other features and advantages of the invention will appear more fully from the detailed description which follows accompanied by drawings showing, for the purpose of illustration, a preferred embodiment of the invention. The invention also resides in certain new and original features of construction and combination of elements hereinafter set forth and claimed.

Although the characteristic features of this invention which are believed to be novel will be particularly pointed out in the claims appended hereto, the invention itself, its objects and advantages, and the manner in which it may be carried out may be better understood by referring to the following description taken in connection with the accompanying drawings forming a part of it in which:

FIG. 1 is a perspective view of a partially assembled machine for carrying out the invention;

FIG. 2 is an elevational view of a portion of the drive mechanism of the machine of FIG. 1;

FIG. 3 is a perspective view of the machine of FIG. 1 at an advanced stage of assembly showing the blank feeder mechanism and a portion of the power mechanism for contracting the die;

FIG. 4 is a perspective bottom view of the power mechanism of FIG. 3;

FIG. 5 is a perspective view of the blank feeder, the plunger and the die of the machine and illustrates a phase of the operation in which a fiat blank approaches the glue applying mechanism above the die;

FIG. 6 shows the blank prefolded at a moment shortly prior to the release by the feeder and prior to the application of adhesive;

FIG. 7 illustrates a later phase of the operation at which the plunger strikes the blank while the feeder approaches the magazine to pick up the next blank;

FIGS. 8, 9 and 10 illustrate successive stages of the forming operation performed on the box, FIG. 10 showing the position in which the plunger as well as the oscillating drive bar has reached its lowest position;

FIG. 11 is a perspective view of a pneumatic actuating mechanism between the drive bar and the plunger proper;

FIG. 12 is a perspective view of the drive mechanism of the machine including the actuator for the glue pump;

FIGS. 13, 14 and illustrate different positions of adjustment of the mechanism for interrupting the feeding of adhesive, FIG. 13 showing a position in which adhesive is about to be fed, FIG. 14 showing the position in which adhesive is being fed and FIG. 15 showing a position in which no adhesive is fed;

FIGS. 16 to are diagrammatic illustrations of operating conditions under which adhesive is being fed and other conditions under which no adhesive is fed;

FIG. 21 is a perspective view of the die with a box therein after withdrawal of the plunger;

FIG. 22 is an elevational view partly in section of a hydraulic snubber; and

FIG. 23 is a diagram of the electric circuit of the machine.

In the following description and in the claims various details will be identified by specific names for convenience. The names, however, are intended to be generic in their application. Corresponding reference characters refer to corresponding parts in the several figures of the drawings.

The drawings accompanying, and forming part of, this specification disclose certain details of the invention for the purpose of explanation of its broader aspects, but it is understood that the details may be modified in various respects without departure from the principles of the invention and that the invention may be incorporated in other structures than the one shown.

FIGURE 1 shows the machine in a state of partial assembly so that portions of the drive may be seen more clearly. The machine comprises a framework 11 supporting a motor 12 on an adjustable mount 13. The mount 13 forms an element of a variable speed drive 14 whose other major element is a V-belt pulley 15 of variable effective diameter.

A V-belt 16 extends over a driven pulley 17 carrying a sprocket gear (not visible) from which a chain 18 extends to a sprocket gear 19 on a pinion shaft 2t When the speed of the drive is reduced by reducing the effective diameter of the pulley 15 the resulting slack of the belt 16 is taken up by moving the motor forward towards the observer on the adjustable mount 13.

The pinion shaft 24) carries a pinion 21 meshing with a large gear 22 on a crank shaft 23 carrying a crank 24 on either end. The crank is not visible in FIG. 1 but shown in FIG. 2.

The mechanism about to be'described is mounted on both sides of the machine and comprises a crank 24 connected by a lower link 25 to a lower oscillating arm 26 whose one end is pivoted to a plate 27 of the framework at 25 and whose other end is pivotally connected to a connecting rod 29. The upper end of the connecting rod 29 is pivotally connected to a cross head member 30 at 31 (see FIG. 3). The cross head member 30 is vertically slidable on a vertical column 32 of the framework and carries a plunger drive bar 33 extending across the front of the machine.

The crank 24 (FIG. 2) is further connected to an oscillating lever 34 by an upper link 35. The oscillating lever 34 is pivotally mounted to the framework intermediate its ends at 36 and moves a connecting rod 37 which actuates a bell crank lever 38. The lever 38 is tiltable on a fixed pivot 39 on the framework and forms an element of a blank feeding mechanism disclosed in greater detail in the prior Patent No. 2,805,060 to Lefief, dated September 3, 1957.

Briefly, the blank feeding mechanism comprises an oscillating gripper bar 40 supported at both ends by identical lever mechanisms, more particularly a pair of double armed gripper arms 41 pivoted at 42 to the first bell crank levers 38. The end of the gripper arm opposite the gripper bar is formed as a track or guideway 43 of U- shaped cross section within which a pivot 44 on one arm of a second bell crank lever 45 is both rotatable and free to slide longitudinally. The second bell crank lever 45 is pivotally mounted at 46 and its other arm 47 is linked to a connecting rod 48 at 49. The connecting rod 48 has its other end pivoted to the first bell crank lever 38 at 50.

The pivots 39 and 46 are supported by castings 51 which form the sides of a substantially U-shaped framework, viewed from above. The back of the framework is formed by a magazine supporting plate 52 whose ends are bolted to the back of the castings 51. The U-shaped framework is open towards the observer and has front arms or extensions 53 adapted to support a box forming die and box compression mechanism to be held in place by knurled nuts 54.

FIGURE 1 shows further a motor-driven vacuum pump 55 from which a suction line 56 extends including flexible tubing leading to suction cups of the blank feeding mechanism and other pneumatically operated elements of the machine. The feeding mechanism is not yet installed in the machine as shown in FIGURE 1, but portions of the flexible tubing of the suction line are visible at 57 above the lever mechanism on the right as well as above the oscillating gripper bar 49 near the center. The operation of the illustrated mechanism will now be described.

The motor 12 drives the driven pulley 17 at a speed determined by the setting of the variable speed drive, and the driven pulley 17 drives the pinion shaft 29 through the chain 18. The pinion 21, in turn, meshes with the gear 22 and turns the crank shaft 23 carrying a crank 24 on either end (FIG. 2). The crank produces oscillation of the lower oscillating arm 26 as a result of which the cross head members 30 on either side, together with the plunger drive bar 3 3 which connects them, move up and down.

Timed with respect to the motion of the plunger drive bar is the motion of the oscillating gripper bar 40 which in. the completed machine carries suction cups for picking up flat blanks at a magazine and transporting them to a position above the forming die. The motion of the oscillating gripper bar 40 is complex and is disclosed in detail in the above mentioned Lefief patent.

Briefly, the motion of the bar 49 is first substantially horizontal towards the observer during which phase a blank standing on edge is separated from a stack of blanks behind it. After the first substantially translatory motion the bar 40 performs a rotary motion above the pivots 42 whereby the blank is turned substantially 90 degrees, or less, until it is horizontal. The second phase of the motion of the bar 40 is followed by a third phase during which the blank is moved in a substantially vertical direction, parallel to itself, whereafter the bar 4t) stops and the feeding mechanism releases the blank. The bar then moves through a return cycle, first upward and away from the blank, then on an are into the position in which it is shown in FIG. 1 and then away from the observer towards the stack of blanks in order to pick up the next blank. The location of the magazine is best seen in FIGS. 6 to 11. FIG. 5 shows the blank and bar 40 during the rotary phase of the motion, FIG. shows the position in which a blank is about to be removed from the magazine and FIG. 6 shows the position in which the blank is about to be released in a substantially horizontal position.

With an understanding of the basic construction and operation of the drive mechanism it will now be easy to follow the construction and the operation of the specific mechanisms for handling the blank, applying adhesive thereto, folding it into box shape and subjecting the shaped box to compression to set the adhesive sufficiently to permit the box to be discharged.

The box forming mechanism comprises a forming die including means for expanding and contracting it for the purpose of first admitting a formed box into the throat of the die and then subjecting it to compressive force.

The die mechanism is best explained by first turning to FIG. 3 showing the mechanism in a state of partial assembly installed in the machine, and to FIG. 4 showing the compression mechanism standing up on end so that its construction and operation can be followed.

Referring first to FIG. 3, the compression unit comprises a heavy box frame 58 having side members 59 with flanges 60 resting on the front arms 53 of the castings 51 and held in place by the knurled nuts 54-. The side members 59 are connected by transverse top plates 61 and bottom plates 62 welded thereto, the whole structure being sufliciently strong to withstand forces of the order of several tons. Two pivot pins 63 extend through the box frame in the back and pivotally support jaw arms 64 and 65, the other ends of which carry front pins 66 extending through apertures 67 in the transverse bottom plate 62.

A hydraulic cylinder 68 provided with an extension 69 is pivotally connected to the right jaw arm 65 by means of the right front pin 66. A piston 70 is slidable in the cylinder and its piston rod 7 1 extends through a stufiing box 72 to the outside. The piston rod is pivotally connected to the left jaw arm 64 by the left front pin 66.

The piston subdivides the cylinder space into a first chamber to which a flexible pressure line 73 leads and a second chamber to which a flexible pressure line 74 extends. It is immediately apparent that excess pressure in line 74 causes the piston to travel to the right as a result of which the jaw arms 64 and 65 are drawn together, Whereas excess pressure in the pressure line 73 causes the piston to travel to the left and the jaw arms to move apart. A pair of stroke limiting screws 75 are provided for limiting the opening movement.

A pair of jaws 76, 77 are mounted for parallel movement on rods 78 in the box frame. Only the rear rod is visible, the front rod being hidden under the transverse plates. The jaws 76 and 77 have substantially cylindrical extensions 79 secured thereto which are grasped by links 89. Each link has a closed end through which the center pin 81 in each iaw arm extends and an open end which grasps the cylindrical extensions 79. By an exchange of a short link by a longer link the spacing of the jaws 76 and 77 may be reduced to handle a box of small size, whereas replacement of the link by a shorter link enlarges the space between the jaws '76 and 77 to accommodate a larger box.

The mounting of the hydraulic cylinder within the box frame 58 is a floating mounting insuring application of equal force to both jaws 76 and 77.

A floating mounting, however, does not automatically insure simultaneous application of force in both directions, in that force may be applied sooner to one jaw than to the other. This would also subject a plunger in the die to one-sided blow. To prevent this from happening centering means are provided which, in the illustrated form, comprise a centering arm 82 pivotally mounted to the box frame at 83. Connecting rods 84- and 35 extend from the centering arm 82 to the bottom ends of the front pins 66 as is particularly well visible in FIG. 4. The linkage comprising the centering lever with its two connecting rods insures an equal distance of travel of both jaws 76 and 77 with respect to the central axis of the frame and simultaneous application of force at both aws.

A hydraulic pump driven by a separate electric motor of approximately two horsepower size is enclosed in a pump housing 86 shown in FIG. 3 and hydraulic lines extend from the pump to a hydraulic control valve 87 combined with a solenoid actuator from which a cable 88 extends to a control switch 89 (FIG. 12). The control switch includes a movable arm on which a roller 90 is mounted resting on the periphery of a control cam 91 on the crank shaft 23.

The compression unit and its controls form the subject matter of a separate copending application, serial No. 797,806, filed March 6, 1959, now Patent No. 2,997,929. For the description of the present invention it is sutficient to state that the control cam 91 operates the control switch 89 in such a way that the hydraulic control valve 87 first directs the application of high hydraulic pressure through pressure line 74 to move the jaws 76 and 77 together, whereafter the hydraulic control valve 87 directs the application of a lower hydraulic pressure through pressure line 73 to move the jaws apart.

The jaws 76 and 77 have tapped holes 92 into which mounting bolts 111 may be screwed (see FIG. 5) for attaching pressure plates 11% matching the exact size of the wall panels of the box to which pressure is to be applied. The pressure plates are preferably slightly smaller than the wall panels of the box so that any excess adhesive which is squeezed out of the gluing joint will not be deposited on the plates and transferred to subsequent boxes.

FIG. 3 also shows an empty magazine gate 93 attached to the magazine supporting plate 52. Box blank supporting bars 94 extend from the magazine gate to the rear. The bars support flat box blanks standing on edge and the magazine gate 93 is so dimensioned that it retains the frontmost blank by a slight marginal overlap suflicient to hold the blanks in place, but permitting withdrawal of blanks, one at a time, by the blank feeder which includes suction cups 95. The suction cups are mounted on a feeder frame 96 including lateral bars 97 attached to the feeder bar 40. The previously mentioned flexible tubing 57 carries vacuum to the cups 95. The magazine construction is disclosed in detail in the Patent 2,642,285 to Baker et al. of June 16, 1953.

FIG. 5 illustrates the plunger and die mechanism fully assembled, in condition for operation.

A die frame 98 is mounted on the box frame 58 by four corner bolts 99, carrying knurled nuts 54. The die frame is provided with curved front and rear die plates 100 and 101, respectively, for folding the front panel and the back panel of the folding box, and side plates 102 and 103 for folding the end panels of the box blank into box forming position. All four plates have downwardly curved lips defining a substantially rectangular die throat 104 above which an appropriately shaped plunger 105 is mounted.

The plunger 195 is supported on the plunger drive bar 33 by a pneumatic mechanism later to be described. At this point it is sufiicient to state that vertical movement of the bar 33 causes the plunger 1115 to move into and out of the die throat in timed intervals.

The front and rear die plates 100 and 191 have slots in them through which spring urged stripper fingers 1&5 protrude whose purpose it is to prevent a formed box from being withdrawn upwardly when the plunger 1115 moves out of the die. The fingers 1% normally protrude into the rectangular throat space, but may be pushed back by a box blank entering the throat. The plunger is appropriately recessed at its front and rear surfaces as shown at 107 to clear the stripper fingers in the event the plunger moves into and out of the die without the blank and to prevent the fingers from catching the plunger during its return stroke in normal operation.

The front and rear surfaces of the die carry opposed box wall deflectors 1118 which, in the illustrated form of the machine, have the shape of a spring loaded ball. Corresponding vertical grooves 109 in the plunger body provide clearance between the box wall deflectors andthe plunger. The deflectors bow in the front and rear walls of a completed box immediately after withdrawal of the plunger so that the distance between the bowed-in portions of the front and rear walls becomes less than the corresponding dimension of the bottom panel of the next box to be formed. As a result, the next box seats on the top edge of the bowed-in wall portions of the last formed box and causes the last formed box to be ejected from the die.

FIG. 21 illustrates the bowing in of the box, the action of the stripper fingers 106- and also shows details of the construction of the die.

Glue heads 112 are mounted at the four corners of the die. Each head is mounted at an angle with respect to the surface of the die frame 98 and includes a front plate 113 having a plurality of discharge apertures 114 arranged in a pattern. Each discharge aperture 114 adapted to discharge a certain volume of adhmive which is supplied to the hollow interior of the glue head by an adhesive supply duct 115. A reservoir 116 contains liquid adhesive which is withdrawn from the reservoir through a duct 117 leading to a glue feeding device, preferably in the form of a positive displacement pump which then pumps adhesive under pressure through the adhesive supply ducts to the several glue heads.

The discharge apertures of the glue heads are normally open to permit periodic discharge of adhesive in response to periodic actuation of the pump, but means are provided for closing some or all of the apertures by moveable pins mounted interiorly of the heads. The glue head nearest the observer in FIG. 21 is provided with a clear plastic cover 118 showing three spring urged blocks 119, 120 and 121 inside the head, each block having a plurality of pins 122 at its front. A shaft 123 carrying a knurled knob 124 at its upper end and a cam or eccentric (not visible) at its lower end serves to adjust the three blocks in such a manner that the pins of one, two or three blocks are withdrawn from their respective discharge apertures whereby the size of the glue pattern may be varied. In one extreme position the blocks with their respective pins close all the discharge apertures, so that clogging of the apertures by drying adhesive is prevented.

Application of adhesive to the flaps F takes place shortly after the flaps F are folded into upwardly slanted position by the feeder and before the plunger 105 engages the blank. Each discharge aperture of the applicators discharges a droplet of adhesive. These droplets are applied in a pattern which is preferably of such outline that no 8 droplets are deposited within a marginal zone of the flaps F.

The adhesive applicator forms the subject matter of a separate copending application, Serial No. 797,792, filed March 6, 1959.

The die frame 98 further supports movable catches 125, each catch comprising a base bracket 126 supporting a latch 127 on a pivot 128, the latch being normally urged towards the throat of the die by a spring 129. The catches serve to hold a blank securely above the throat of the die after the blank is deposited by the blank feeder so that the blank does not change its position by reason of air drafts, vibration, etc. during the approach of the plunger 105.

FIG. 5 shows the plunger 105 during its upstroke and also shows the feeding mechanism moving a blank B towards the die. 'In the position shown in FIG. 5 the gripper bar 40 of the feeder performs a rotary motion and moves on an arc to which the plane of the blank B is substantially tangential.

FIG. 6 illustrates the end of the feed stroke during which the feeder performs a translatory motion to deposit the blank above the die throat. During tln's phase of the feeding motion the four glue flaps F of the blank first strike the four glue heads which act as prefolding elements and cause the flaps to be folded into an angular position with respect to the remainder of the blank B. At the end of the feed stroke the unfolded portion of the blank comes to rest on the horizontal portions of the die plate as seen, for extmple, at 100, and the blank snaps underneath the four catches 125 which hold it securely in place during the subsequent return motion of the feeder.

In the prefolded position, the flaps F assume substantially the same angle as the front plates 11.3 of the glue heads and either rest against the glue heads or are spaced therefrom by a very narrow gap of the order of a millimeter or less. This can simply be accomplished by setting the glue heads at 'a slant slightly different from the slant of the flaps F.

The blank B is now released by an appropriate vent valve in the vacuum line 57 leading to the suction cups 95. The valve, which will be referred to later in connection with FIGS. 17 to 21, admits atmospheric air into the line 57 near the vacuum cups as a result of which the cups release the blank. The blank feeder then begins its return stroke and moves out of the way of the plunger which descends to strike the bottom panel of the box blank as shown in FIG. 7.

During the time the blank B is at rest the glue pump makes a feed stroke to discharge a measured quantity of adhesive through the four glue heads 112. Asa result a pattern of predetermined outline of adhesive is deposited on each of the flaps F. Details of the mechanism for actuating the glue pump will later be described in connection with FIGS. 17 to 21.

As the plunger enters the die the front and back panels whose edges were caught under the catches are withdrawn therefrom and are folded upwardly as shown in FIG. 8. The glue flaps F remain at an angle with respect to the front and back panels of the box and are being folded about the plunger briefly prior to the folding of the outer side walls of the box into upright position on top of the glue flaps F.

FIG. 9 shows the plunger 105 in a position in which the folding of the box blank B is nearly complete and the box has entered the throat of the die except for its top portion which is still visible above the front plate 100 and the side plate 102.

FIG. 10 shows the plunger at the bottom of its stroke and the plunger drive bar 33 at its lowest position. At this instant the compression unit is actuated by applying high pressure through the line 74 to contract the die. The pressure which is applied is of the order of 2000 pounds per square inch applying a force of the order of flve to six tons at the jaws 76 and 77. The jaws press against the side walls of the box with their pressure plates 1111 (see FIG. 3 showing the jaws and FIG. 5 showing the pressure plate). The applied pressure causes the adhesive to be distributed over the flaps F as a very thin film which begins to set immediately due to the fact that the amount of solvent to be absorbed by the board per unit of area is very small. Under these conditions the adhesive becomes highly tacky immediately and produces a secure bond, although the application of pressure is quite short, of the order of a fraction of a second.

The travel of the jaws is short and is maintained as small as possible by an appropriate setting of the stroke limiting screws 7 5 shown in FIG. 3.

The stroke centering device, more particularly the centering lever 82 and the connecting rods 84 and 85 (FIG. 4) insure simultaneous application of the force by both jaws 76 and 77 of the compression unit, so that the plunger is not subjected to a lateral blow by one jaw striking before the other.

Although an application of compressive force during a period of the order of one-fifth of a second is satisfactory, it is preferred to maintain the force as long as is consistent with the rate of operation of the machine.

As previously mentioned, the plunger drive bar 33 moves up and down continuously and never comes to rest except at the return points at the ends of the up and down stroke, respectively. It is not practicable to arrest the plunger drive bar during the period of application of compressiv'e force due to the mass of the mechanism which would have to be stopped and then accelerated from rest.

It is thus readily seen that it is not practicable to mount the plunger directly on the drive bar 33 which continues to move while the plunger must remain at rest during the compression cycle. Also, it is necessary to accelerate the plunger gradually from a position of rest without a resulting pounding in the drive mechanism by reason of the inertia of the masses involved.

A pneumatic mechanism is provided which suspends the plunger from the drive bar. This mechanism forms the subject matter of a separate copending application, Serial No. 797,676, filed March 6, 1959, now Patent No. 2,997,928.

The plunger drive bar 33 (FIGS. and 11) carries two brackets 130 and 13 1 on which a common base plate 132 is mounted. The base plate 132 carries two vertical cylinders 133 and 134, each containing a piston 135 and 136 whose piston rods 137 and 13% extend through the top of the cylinders and are connected by a piston plate 139.

The top ends of the cylinders 133 and 134 are held in place by a top plate 141} which is rigidly connected to the base plate 132 by four spacer rods 14-1. The front rods are visible in FIG. 11 while a rearward rdd is also seen in PEG. 10. Two slide bearing sleeves 142 and 143 are also held between the base plate 132 and the top plate 141?. Plunger rods 144 and 145 extend slidably through the sleeves M2 and 143 and carry a plunger plate 146 at their lower ends. The plunger 105 is secured to the plunger plate 146 by a bolt 147.

The pistons 135 and 136 divide the cylinders into upper chambers and lower chambers, the upper chambers being in communication with the atmospheric air through air filters 14-8 which keep out dust. The lower chambers are in communication with the atmosphere through similar filters 14%. Valve assemblies 149 and 150 are interposed between the lower chambers and the atmosphere, the assembly 159 being mounted upside down with respect to the valve assembly 14$. Comparing FIG. 10 with FIG. 11 it will be noted that the valve assemblies 149 and 151) were rotated 90 degrees in FIG. 11 with respect to the position in which they are shown in FIG. 10. This was merely done to show the inverted mounting in both figures which would not he noticeable if the assemblies had not been rotated for the purpose of illustration.

Each valve assembly comprises basically a housing tapped at both ends for threaded connection with appropriate fittings. Intermediate its ends the housing is divided by an internal cross wall not shown in the drawings. The internal wall has two apertures through which the upper portion of the housing may communicate with the lower portion. One of these apertures is. variable in size by a needle valve N, the other is controlled by a check valve C. The needle valve permits restricted passage of air through the valve assembly in the direction of the axis of the valve housing. The check valve permits relatively free flow of air in one direction, but seals its passage when the air flows in the opposite direction.

As a result of the inverted mounting of valve assembly 15% with respect to the assembly 149, atmospheric air enters freely into the lower chamber of the cylinder 134 when its piston moves upwardly, whereas downward motion of the same piston meets with resistance because air being forced out of the lower chamber causes the check valve C to close and can escape only through the restricted needle valve N. Thus downward motion of the piston within the right cylinder 134 is restrained whereas upward motion is unrestrained.

The reverse applies with respect to the piston within the left cylinder 133. Upward piston motion, causing air to enter its lower chamber, is restrained because air can only enter through its needle valve N while its check valve C is closed. Downward motion, however, causing air to escape from the lower chamber, is unrestrained because the air escapes freely through the check valve C.

An adustment of the needle valve N permits any desired degree of restraint to be imposed on the upward motion and the downward motion of the pistons with respect to the cylinders and thus upon the plunger with respect to its drive bar 33. The restraint is of an elastic nature due to the compressibility and the expansibility of air.

In order to prevent the pistons from bottoming in the respective cylinders 133 and 134 a pair of butters 151 are mounted on the top plate on which stops 152 on piston plate 139 may seat.

It was previously mentioned that the downward motion of the plunger 195 is arrested in the position in which compressive force is exerted on the folding box.

In order to prevent sudden stops of the plunger from producing a corresponding impact on the drive a hydraulic snubber mechanism is provided comprising a snubber cylinder 153 mounted on the framework 11 on the machine and a striker pad 154 on the piston plate 139'. When the striker pad 154 seats on the rod 155 of the snubber piston 158 enclosed in the snubber cylinder 153 (see also FIG. 23), liquid 159 is displaced past the piston through a narrow passage let which is restricted increasingly the farther the piston moves. A reservoir 156 is in communication with the snubber cylinder 153 through a hydraulic line 157. A spring 161 returns the piston 158 to a normal rest position. The variable flow resistance in the liquid passage causes the end of the snubber 155 to oifer increasing resistance to the downward motion of the piston plate 13%, and arrests plunger gently.

It is now readily seen that once the plunger 105 has reached its lowest position in the throat or" the folding die, and is temporarily clamped by reason of the action of the compression unit, the plunger drive bar 33 may start its upward motion without delay. During the upward motion of the bar 33 the cylinders 133 and 13-;- move into an upward direction with respect to their pistons which are at rest by reason of being attached to the plunger. During this motion air is compressed in the lower chamber of the cylinder 134, and escapes only slowly because of the restriction of air flow by the needle valve N of the assembly 150. This compressed air represents a resilient driving force which drives the plunger 1&5 upwardly as soon as the compressive force by the compression unit is released. This action is gentle and continues until the pistons are raised so far that the stops 152 seat on the buffers 151, 

